Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 291159
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
659 AM CDT MON JUN 29 2015

.AVIATION...
FOR THE 12Z TAFS... MAIN AVIATION CONCERNS CENTER AROUND LOW
CLOUDS AND MVFR VISIBILITIES THIS MORNING AT KCLL/KUTS/KCXO/KLBX
AND TSRA/SHRA DEVELOPMENT TODAY NEAR THE TERMINALS.

LOWERING CEILINGS AND MVFR VISIBILITIES FOR KCLL/KUTS/KCXO/KLBX
THIS MORNING EXPECTED TO PERSIST THROUGH 13-14Z THIS MORNING
BEFORE ONSET OF DAYTIME HEATING IMPROVES CONDITIONS. DAYTIME
HEATING AND SEA BREEZE DEVELOPMENT TODAY EXPECTED TO CONTRIBUTE TO
ISOLATED TO SCATTERED TSRA ACROSS SOUTHEAST TEXAS GENERALLY AFTER
17Z. ENVIRONMENTAL CONDITIONS THIS AFTERNOON WILL NOT ONLY FAVOR
BRIEF HEAVY DOWNPOURS LIMITING VISIBILITIES AT THE TERMINALS...
BUT GUSTY AND ERRATIC WINDS IN AND NEAR ANY THUNDERSTORM. HAVE
INCLUDED TEMPO MENTION FOR THE HOUSTON TERMINALS THIS AFTERNOON...
WITH ADDITIONAL REFINEMENT TO TIMING EXPECTED IN FUTURE TAFS.
ANTICIPATE ACTIVITY TO DISSIPATE WITH LOSS OF DAYTIME HEATING.

LIGHT AND VARIABLE WINDS EXPECTED TO BECOME SOUTHERLY AROUND 5 TO
10 KNOTS THROUGH THE PERIOD... WITH VFR CONDITIONS EXPECTED TO
PREVAIL OUTSIDE OF TSRA. WITH RECENT RAINFALL AND OVERNIGHT
CLEARING... COULD SEE SOME PATCHY BR/ MVFR VISIBILITIES MAINLY
NORTH AND NORTHWEST OF THE HOUSTON TERMINALS TUESDAY MORNING BUT
CONFIDENCE TOO LOW TO INCLUDE IN TAFS AT THE MOMENT.

HUFFMAN

&&

.PREV DISCUSSION... /ISSUED 356 AM CDT MON JUN 29 2015/

DISCUSSION...
A WEAK SURFACE HIGH PRESSURE RIDGE WAS SITUATED OVER SE TEXAS
EARLY THIS MORNING. THE 200 AND 300 MB UPPER LOW OVER THE WESTERN
GULF OF MEXICO HAS DRIFTED EASTWARD OVER THE PAST 24 TO 30 HOURS.
AT 500 MB THE FORECAST AREA CONTINUED UNDER A WEAKNESS IN THE
RIDGE...ALTHOUGH THERE WAS A TROUGH AXIS OVER THE LOWER MS VALLEY
WHICH HAS PLACED A NORTHWESTERLY FLOW OVER THE AREA. THE WEAK
NORTHWEST FLOW CAN ALSO BE SEEN ON THE LATEST WATER VAPOR LOOP OF
THE PAST 9 HOURS AND THE RAP40 ANALYSIS OF THE 700 TO 300 MB MEAN
FLOW. THE NAMBUFR MODEL SOUNDINGS FORECAST SURFACE BASED CAPE
VALUES BETWEEN 2500 AND 3400 AT 4 AM WITH THE MOST UNSTABLE
CONDITIONS NEAR AND OFF THE COAST.

FOR TODAY...THE HIGH RES MODELS ARE CONSISTENT IN SHOWING THE
DEVELOPING SHOWERS ALONG THE COAST. THERE WAS ALSO ISOLATED
CONVECTION IN THE NORTHWEST FLOW OVER OK AND THE RED RIVER VALLEY
TOWARD THE PAN HANDLE. A CONSENSUS OF THE MODELS SHOWS SCATTERED
SHOWERS AND THUNDERSTORMS DEVELOPING THIS MORNING ACROSS SE TEXAS
AND PERSISTING INTO AT LEAST THE MID AFTERNOON. GIVEN THE LIGHT
FLOW ALOFT THINK THAT THE SEABREEZE WILL ALSO PLAY A FACTOR IN
ADDITION TO ANY OUTFLOW BOUNDARIES THAT SET UP.

THE MODELS KEEP THE WEAKNESS ALOFT IN PLACE THROUGH THE REMAINDER
OF THE WEEK AND INTO THE UPCOMING WEEKEND. THE RIDGE DOES APPEAR
TO STRENGTHEN A BIT ON BOTH THE GFS AND ECWMF OVER THE LATTER HALF
OF THE WEEK AS THE TROUGH OVER THE GREAT LAKES AND MID MS VALLEY
MOVES EASTWARD. HOWEVER...A FAIRLY MOIST AND UNSTABLE AIRMASS WILL
REMAIN OVER SE TEXAS AS THE RIDGING ALOFT APPEARS TO BE TOO WEAK
TO ADVERSELY AFFECT RAIN CHANCES UNTIL THURSDAY AND FRIDAY.
ANOTHER TROUGH DIGS INTO THE SOUTHERN PLAINS FROM THE GREAT LAKES
OVER THE WEEKEND.

40

MARINE...
LITTLE CHANGE TO ONGOING MARINE FORECAST WITH LIGHT TO
OCCASIONALLY MODERATE ONSHORE WINDS EXPECTED TO PERSIST OVER THE
NEXT SEVERAL DAYS. WITH SOUTHERLY FLOW BECOMING ESTABLISHED TODAY
/AS OPPOSED TO THE SOUTHWEST TO WESTERLY WINDS OBSERVED
YESTERDAY/... TIDE LEVELS HAVE BEGUN TO RETURN TO NEAR NORMAL
VALUES. INTERMITTENT CHANCES FOR SHOWERS AND THUNDERSTORMS WILL
PERSIST OVER THE COASTAL WATERS THROUGH MID-WEEK... WITH A BRIEF
RESPITE POSSIBLE IN THE THURSDAY FRIDAY TIMEFRAME AS RIDGING
BUILDS IN FROM THE EAST. RAIN CHANCES... AS WELL AS ELEVATED WINDS
AND WAVES... RETURN FOR THE UPCOMING HOLIDAY WEEKEND AS A SURFACE
HIGH STRENGTHENS OVER THE EASTERN GULF AND AN UPPER DISTURBANCE
REACHES TEXAS.

HUFFMAN

&&

.PRELIMINARY POINT TEMPS/POPS...
COLLEGE STATION (CLL)      90  74  90  73  92 /  30  20  40  10  30
HOUSTON (IAH)              91  75  91  74  92 /  40  20  40  20  40
GALVESTON (GLS)            89  82  89  81  90 /  40  20  40  30  40

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&

$$

AVIATION/MARINE...14



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